Intra-event spatial correlation of ground motion using L'Aquila earthquake ground motion data

The intensities f ground motions and structural responses at two sites are correlated. The magnitude of the correlation depends on the distance between the sites and the natural vibration period of the structures. Spatial correlation of intra-event peak ground motion amplitudes at different sites is an important issue for seismic hazard and risk assessment of spatially distributed buildings and infrastructures. Correlated seismic effects cause acute concentration and accumulation of seismic losses, potentially resulting in a catastrophic event. The adequacy of the existing spatial correlation model has been checked using the L'Aquila earthquake ground motion data. Spatial correlations based on the L'Aquila earthquake data decreases gradually with increasing inter-station separation distance. At short separation distances, the estimated spatial correlation data points show large variability around the average trend. At short separation distances such as 1 km, where empirical data are limited and estimates are uncertain, discretion is required in adopting such models for seismic hazard and risk assessment of spatially distributed structures.